How can I allow the game to access my friends list on Facebook to use social features in the game?

When you start playing, the game asks for your permission to get access to your friends list. All you need is to confirm the info you provide. In case you rejected the request, you can edit the settings for your app here:
1. Click on the arrow button in the top right of Facebook.
2. Select Settings in the drop-down menu.
3. Click on Apps in the left column.
4. Hover over the game and click on it.
5. Check for the Friend list option to be turned on: http://take.ms/gZuze
6. Click on Save to confirm the changes.